Question

The absolute enthalpy of neutralisation of the reaction, $ MgO(s)+2HCl(aq)\xrightarrow{{}}MgC{{l}_{2}}(aq)+{{H}_{2}}O(l) $ will be

• A. less than -57.33 kJ $ mo{{l}^{-1}} $
• B. -57.33 kJ $ mo{{l}^{-1}} $
• C. greater than -57.33 kJ $ mo{{l}^{-1}} $
• D. 57.33 kJ $ mo{{l}^{-1}} $

Answer 1

Answer: (A)

Heat of neutralisation of strong acid and strong base is -57.33 kJ. MgO is a weak base while HCl is a strong add, so the heat o neutralisation of MgO and HCl is lower than -57.33 kJ because MgO requires some heat in ionisation, then net released amount of heat is decreased.